Boulder weather in October

In October, Boulder sees average daytime highs of 58°F and overnight lows near 33°F, with 1.9 in of precipitation across 7.4 wet days and about 10.9 hours of daylight. It is the 6th-warmest and 8th-wettest month of the year here.

Highs ease over the month, from about 64°F in the first days to 52°F by the end. The sky is clear or mostly clear about 54% of the time in October, and the air most often feels dry.

Daylight stretches from about 11 h 36 min at the start of October to 10 h 18 min by month's end. Set against the rest of the year, October is Boulder's 2nd-clearest and 7th-windiest month. For the whole year in context, see Boulder's year-round climate.

Daytime high: 58°; 6th warmest
Overnight low: 33°; 7th coldest
Precipitation: 1.9 in; 7.4 wet days
Daylight: 10 h 54 min; 6:18 AM – 5:14 PM
Cloud cover: 42%; 2nd clearest
Wind: 5 mph; 7th windiest
Solar energy: 4.09 kWh/m²
Travel score: 4.9; out of 10

Boulder is city in and county seat of Boulder County, Colorado, United States.

Density: 1,606/km²; people per km²
Founded: 1858

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

← September Boulder year-round climate November →Best places to visit in October

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Temperature in October

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 64°F in the first days to 52°F by the end.

A typical October day in Boulder reaches about 58°F in the afternoon and slips back to 33°F overnight — a 25°F spread between the day's warmth and the night's chill. On most days the high lands between 43°F and 72°F. Set against its neighbours, October runs about 12°F cooler than September and about 13°F warmer than November.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Avg high (°F)	65	65	64	64	63	63	62	62	62	61	61	60	60	60	59	59	58	58	57	57	56	56	55	55	54	54	53	53	52	52	51
Avg low (°F)	39	38	38	38	37	37	36	36	36	35	35	35	34	34	33	33	33	32	32	32	31	31	31	30	30	29	29	29	28	28	28

	Avg high (°F)	Avg low (°F)
1	65	39
2	65	38
3	64	38
4	64	38
5	63	37
6	63	37
7	62	36
8	62	36
9	62	36
10	61	35
11	61	35
12	60	35
13	60	34
14	60	34
15	59	33
16	59	33
17	58	33
18	58	32
19	57	32
20	57	32
21	56	31
22	56	31
23	55	31
24	55	30
25	54	30
26	54	29
27	53	29
28	53	29
29	52	28
30	52	28
31	51	28

How October really feels in Boulder

Once humidity and wind are folded in, October averages 0 days that feel above 90°F and 24 that feel at or below 32°F — the comfort signal a plain temperature reading hides.

Days feeling ≥ 90°F

heat index over the day's high

Days feeling ≤ 32°F

wind chill below the day's low

The story in October is cold — wind chill drags the overnight "feels like" below the raw low.

Boulder weather by month

How October compares with the rest of the year at a glance. October is the 6th-warmest and 8th-wettest month here — the current month is highlighted below.

Month	High / Low (°F)	Rainfall (inches)	Wet days	Snow days	Daylight (hours)	Travel score
Jan	37° / 14°	0.9	5.7	5.5	9.5	0.0
Feb	39° / 16°	1.0	6.7	7	10.4	0.0
Mar	48° / 22°	2.0	8.8	7.2	11.7	1.7
Apr	54° / 29°	3.1	11.1	7.9	13	3.1
May	63° / 38°	4.0	14.9	3.5	14.2	4.8
Jun	74° / 47°	3.0	14.3	0.3	14.8	6.2
Jul	80° / 53°	3.0	14.8	0	14.5	6.0
Aug	78° / 52°	2.8	14.9	0	13.6	6.2
Sep	71° / 44°	2.1	9.7	0.9	12.3	6.8
Oct	58° / 33°	1.9	7.4	3.9	10.9	4.9
Nov	46° / 22°	1.3	6.4	5.7	9.8	1.4
Dec	37° / 15°	0.9	5.3	5.4	9.2	0.0

Cloud cover in October

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 54% of the time in October.

Beyond those clear spells, partly cloudy skies cover about 16% of October, with mostly cloudy or overcast conditions the remaining 30%.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Clearer (%)	70	69	70	70	70	70	70	71	71	71	72	72	72	72	72	72	72	72	71	70	70	69	69	67	67	66	67	67	67	67	67
Cloudier (%)	30	31	30	30	30	30	30	29	29	29	28	28	28	28	28	28	28	28	29	30	30	31	31	33	33	34	33	33	33	33	33

	Clearer (%)	Cloudier (%)
1	70	30
2	69	31
3	70	30
4	70	30
5	70	30
6	70	30
7	70	30
8	71	29
9	71	29
10	71	29
11	72	28
12	72	28
13	72	28
14	72	28
15	72	28
16	72	28
17	72	28
18	72	28
19	71	29
20	70	30
21	70	30
22	69	31
23	69	31
24	67	33
25	67	33
26	66	34
27	67	33
28	67	33
29	67	33
30	67	33
31	67	33

Chance of precipitation in October

Any precipitationSnow

Boulder gets around 1.9 in of rain and snow over 7.4 wet days in October. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable precipitation averages around 23% and peaks near 27% on the wettest days, and about 4 days bring snow.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Rain chance (%)	27	26	26	26	26	26	25	25	24	24	23	23	22	21	21	21	21	21	21	21	21	22	22	23	23	24	24	24	24	24	24
Snow chance (%)	7	7	7	8	8	8	9	9	9	10	10	10	10	11	11	11	12	12	13	13	14	14	15	16	16	17	17	17	17	18	18

	Rain chance (%)	Snow chance (%)
1	27	7
2	26	7
3	26	7
4	26	8
5	26	8
6	26	8
7	25	9
8	25	9
9	24	9
10	24	10
11	23	10
12	23	10
13	22	10
14	21	11
15	21	11
16	21	11
17	21	12
18	21	12
19	21	13
20	21	13
21	21	14
22	22	14
23	22	15
24	23	16
25	23	16
26	24	17
27	24	17
28	24	17
29	24	17
30	24	18
31	24	18

Humidity in October

DryComfortableHumidMuggyOppressiveMiserable

Most of October feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, October lands in the dry band about 100% of days. It rarely turns muggy — the humid and sticky bands barely register.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Dry (%)	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100

	Dry (%)
1	100
2	100
3	100
4	100
5	100
6	100
7	100
8	100
9	100
10	100
11	100
12	100
13	100
14	100
15	100
16	100
17	100
18	100
19	100
20	100
21	100
22	100
23	100
24	100
25	100
26	100
27	100
28	100
29	100
30	100
31	100

Wind in October

Winds average 5 mph in October.

Across October, daily wind ranges from about 5 mph on the calmest days to 5 mph at its breeziest. It stays fairly steady from day to day.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Wind speed (mph)	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5
Feels	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm

	Wind speed (mph)	Feels
1	5	calm
2	5	calm
3	5	calm
4	5	calm
5	5	calm
6	5	calm
7	5	calm
8	5	calm
9	5	calm
10	5	calm
11	5	calm
12	5	calm
13	5	calm
14	5	calm
15	5	calm
16	5	calm
17	5	calm
18	5	calm
19	5	calm
20	5	calm
21	5	calm
22	5	calm
23	5	calm
24	5	calm
25	5	calm
26	5	calm
27	5	calm
28	5	calm
29	5	calm
30	5	calm
31	5	calm

Sunrise & sunset in October

DaylightNight

Daylight runs from about 11 h 36 min at the start of October to 10 h 18 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 78 minutes over October. Sunrise moves from 6:03 AM to 6:35 AM, and sunset from 5:38 PM to 4:54 PM.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Daylight (h)	11.6	11.5	11.5	11.4	11.4	11.4	11.3	11.3	11.2	11.2	11.1	11.1	11.1	11.0	11.0	10.9	10.9	10.8	10.8	10.8	10.7	10.7	10.6	10.6	10.5	10.5	10.5	10.4	10.4	10.3	10.3
Sunrise (AM)	6:03	6:04	6:05	6:06	6:07	6:08	6:09	6:10	6:11	6:12	6:13	6:14	6:15	6:16	6:17	6:18	6:20	6:21	6:22	6:23	6:24	6:25	6:26	6:27	6:28	6:30	6:31	6:32	6:33	6:34	6:35
Sunset (PM)	5:38	5:36	5:34	5:33	5:31	5:29	5:28	5:26	5:25	5:23	5:21	5:20	5:18	5:17	5:15	5:14	5:12	5:11	5:09	5:08	5:07	5:05	5:04	5:03	5:01	5:00	4:59	4:57	4:56	4:55	4:54

	Daylight (h)	Sunrise (AM)	Sunset (PM)
1	11.6	6:03	5:38
2	11.5	6:04	5:36
3	11.5	6:05	5:34
4	11.4	6:06	5:33
5	11.4	6:07	5:31
6	11.4	6:08	5:29
7	11.3	6:09	5:28
8	11.3	6:10	5:26
9	11.2	6:11	5:25
10	11.2	6:12	5:23
11	11.1	6:13	5:21
12	11.1	6:14	5:20
13	11.1	6:15	5:18
14	11.0	6:16	5:17
15	11.0	6:17	5:15
16	10.9	6:18	5:14
17	10.9	6:20	5:12
18	10.8	6:21	5:11
19	10.8	6:22	5:09
20	10.8	6:23	5:08
21	10.7	6:24	5:07
22	10.7	6:25	5:05
23	10.6	6:26	5:04
24	10.6	6:27	5:03
25	10.5	6:28	5:01
26	10.5	6:30	5:00
27	10.5	6:31	4:59
28	10.4	6:32	4:57
29	10.4	6:33	4:56
30	10.3	6:34	4:55
31	10.3	6:35	4:54

Solar energy in October

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in October, about 4.09 kWh/m².

For context, solar energy here swings from a low near 2.56 kWh/m² to a high of 7.49 kWh/m² in June across the year — October's 4.09 kWh/m² falls in the middle.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Solar energy (kWh/m²)	4.8	4.7	4.7	4.6	4.6	4.5	4.5	4.5	4.4	4.4	4.3	4.3	4.3	4.2	4.2	4.1	4.1	4.0	4.0	4.0	3.9	3.9	3.8	3.8	3.7	3.7	3.6	3.6	3.6	3.5	3.5
Level	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate

	Solar energy (kWh/m²)	Level
1	4.8	Bright
2	4.7	Bright
3	4.7	Bright
4	4.6	Bright
5	4.6	Bright
6	4.5	Bright
7	4.5	Bright
8	4.5	Bright
9	4.4	Bright
10	4.4	Bright
11	4.3	Bright
12	4.3	Bright
13	4.3	Bright
14	4.2	Bright
15	4.2	Bright
16	4.1	Bright
17	4.1	Bright
18	4.0	Bright
19	4.0	Moderate
20	4.0	Moderate
21	3.9	Moderate
22	3.9	Moderate
23	3.8	Moderate
24	3.8	Moderate
25	3.7	Moderate
26	3.7	Moderate
27	3.6	Moderate
28	3.6	Moderate
29	3.6	Moderate
30	3.5	Moderate
31	3.5	Moderate

Planning a trip in October

Hazard calendar for Boulder

In seasonPeak

In October, Boulder sits inside its rainy season season. The full year is below, with each hazard's peak months called out.

Boulder's rainy season runs March–October, when most of the year's rain falls.

Rainy season

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Is October a good time to visit Boulder?

Our two travel scores rate October for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).

4.9

Sightseeing

5th-best month of the year

0.7

Beach & pool

6th-best month of the year

October is a reasonable time to visit Boulder for sightseeing.

What to pack for Boulder in October

From October's temperature range, rain chance, sun and wind — what's worth putting in the bag.

In October, Boulder sees daytime highs around 58°F and nights near 33°F. Worth packing: a warm layer. About 7 days see rain.

a warm layer

UV index in Boulder in October

LowModerateHighVery highExtreme

Clear-sky midday UV in October peaks around 5 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Boulder peaks around July 13 at about 11 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 23 at about 2 (moderate).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 10 months of the year.

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
UV index (midday)	2	4	7	6	7	11	11	10	7	5	3	2
Level	Moderate	Moderate	High	High	Very high	Extreme	Extreme	Very high	Very high	High	Moderate	Low

	UV index (midday)	Level
Jan	2	Moderate
Feb	4	Moderate
Mar	7	High
Apr	6	High
May	7	Very high
Jun	11	Extreme
Jul	11	Extreme
Aug	10	Very high
Sep	7	Very high
Oct	5	High
Nov	3	Moderate
Dec	2	Low

Air quality in Boulder in October

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where October falls, not just the annual average.

Air quality in Boulder is worst in August — around 21 µg/m³ PM2.5 (moderate), about 1.6× the cleanest month (May, 13 µg/m³).

Modeled monthly averages (CAMS reanalysis, 2015–2024).

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
PM2.5 (µg/m³)	17	15	16	13	13	14	14	21	13	15	15	16
Level	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate

	PM2.5 (µg/m³)	Level
Jan	17	Moderate
Feb	15	Moderate
Mar	16	Moderate
Apr	13	Moderate
May	13	Moderate
Jun	14	Moderate
Jul	14	Moderate
Aug	21	Moderate
Sep	13	Moderate
Oct	15	Moderate
Nov	15	Moderate
Dec	16	Moderate

Location & terrain

Where is Boulder?

Boulder sits at 40.0°N, 105.3°W, 5,328 ft above sea level, in United States. The nearest listed city is Louisville, 8.1 mi away.

Topography around Boulder

How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Boulder.

Within 2 miles, the terrain around Boulder has significant variations in elevation — a maximum elevation change of 1,703 ft around an average of 5,495 ft above sea level; within 10 miles, very significant variations in elevation — a maximum elevation change of 4,147 ft; within 50 miles, extreme variations in elevation — a maximum elevation change of 9,623 ft.

The land around Boulder is covered by trees (45%) and artificial surfaces (39%) within 2 miles, grassland (44%) and trees (41%) within 10 miles, and trees (41%) and grassland (34%) within 50 miles.

2 miles

1,703 ft

trees 45%

10 miles

4,147 ft

grassland 44%

50 miles

9,623 ft

trees 41%

treesgrasslandcroplandartificial surfacesbare terrainwatermoss and lichen

← September Boulder year-round climate November →Best places to visit in October

October weather nearby: Louisville 8.1 mi · Lafayette 9.9 mi · Broomfield 12 mi · Erie 12 mi · Longmont 14 mi · Westminster 17 mi · Northglenn 17 mi · Arvada 17 mi

United States travel facts

Power plugs: Type A / B; 120 V · 60 Hz
Prices: ≈ 100% of US; price level, 2025
GDP per capita: $90,027; 2025
Happiness: 6.8 / 10; World Happiness, 2025
Safe drinking water: 98%; of population, 2024
Homicide rate: 5.8; per 100k, 2023
Road deaths: 12.7; per 100k/yr, 2019
Income group: High; World Bank
Religion

Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.

Data sources

Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Boulder (40.015°, -105.2706°, elevation 5,328 ft), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).

	Avg high (°F)	Avg low (°F)
1	65	39
2	65	38
3	64	38
4	64	38
5	63	37
6	63	37
7	62	36
8	62	36
9	62	36
10	61	35
11	61	35
12	60	35
13	60	34
14	60	34
15	59	33
16	59	33
17	58	33
18	58	32
19	57	32
20	57	32
21	56	31
22	56	31
23	55	31
24	55	30
25	54	30
26	54	29
27	53	29
28	53	29
29	52	28
30	52	28
31	51	28

	Clearer (%)	Cloudier (%)
1	70	30
2	69	31
3	70	30
4	70	30
5	70	30
6	70	30
7	70	30
8	71	29
9	71	29
10	71	29
11	72	28
12	72	28
13	72	28
14	72	28
15	72	28
16	72	28
17	72	28
18	72	28
19	71	29
20	70	30
21	70	30
22	69	31
23	69	31
24	67	33
25	67	33
26	66	34
27	67	33
28	67	33
29	67	33
30	67	33
31	67	33

	Rain chance (%)	Snow chance (%)
1	27	7
2	26	7
3	26	7
4	26	8
5	26	8
6	26	8
7	25	9
8	25	9
9	24	9
10	24	10
11	23	10
12	23	10
13	22	10
14	21	11
15	21	11
16	21	11
17	21	12
18	21	12
19	21	13
20	21	13
21	21	14
22	22	14
23	22	15
24	23	16
25	23	16
26	24	17
27	24	17
28	24	17
29	24	17
30	24	18
31	24	18

	Dry (%)
1	100
2	100
3	100
4	100
5	100
6	100
7	100
8	100
9	100
10	100
11	100
12	100
13	100
14	100
15	100
16	100
17	100
18	100
19	100
20	100
21	100
22	100
23	100
24	100
25	100
26	100
27	100
28	100
29	100
30	100
31	100

	Avg high (°F)	Avg low (°F)
1	65	39
2	65	38
3	64	38
4	64	38
5	63	37
6	63	37
7	62	36
8	62	36
9	62	36
10	61	35
11	61	35
12	60	35
13	60	34
14	60	34
15	59	33
16	59	33
17	58	33
18	58	32
19	57	32
20	57	32
21	56	31
22	56	31
23	55	31
24	55	30
25	54	30
26	54	29
27	53	29
28	53	29
29	52	28
30	52	28
31	51	28

	Clearer (%)	Cloudier (%)
1	70	30
2	69	31
3	70	30
4	70	30
5	70	30
6	70	30
7	70	30
8	71	29
9	71	29
10	71	29
11	72	28
12	72	28
13	72	28
14	72	28
15	72	28
16	72	28
17	72	28
18	72	28
19	71	29
20	70	30
21	70	30
22	69	31
23	69	31
24	67	33
25	67	33
26	66	34
27	67	33
28	67	33
29	67	33
30	67	33
31	67	33

	Rain chance (%)	Snow chance (%)
1	27	7
2	26	7
3	26	7
4	26	8
5	26	8
6	26	8
7	25	9
8	25	9
9	24	9
10	24	10
11	23	10
12	23	10
13	22	10
14	21	11
15	21	11
16	21	11
17	21	12
18	21	12
19	21	13
20	21	13
21	21	14
22	22	14
23	22	15
24	23	16
25	23	16
26	24	17
27	24	17
28	24	17
29	24	17
30	24	18
31	24	18

	Dry (%)
1	100
2	100
3	100
4	100
5	100
6	100
7	100
8	100
9	100
10	100
11	100
12	100
13	100
14	100
15	100
16	100
17	100
18	100
19	100
20	100
21	100
22	100
23	100
24	100
25	100
26	100
27	100
28	100
29	100
30	100
31	100

	Avg high (°F)	Avg low (°F)
1	65	39
2	65	38
3	64	38
4	64	38
5	63	37
6	63	37
7	62	36
8	62	36
9	62	36
10	61	35
11	61	35
12	60	35
13	60	34
14	60	34
15	59	33
16	59	33
17	58	33
18	58	32
19	57	32
20	57	32
21	56	31
22	56	31
23	55	31
24	55	30
25	54	30
26	54	29
27	53	29
28	53	29
29	52	28
30	52	28
31	51	28

	Clearer (%)	Cloudier (%)
1	70	30
2	69	31
3	70	30
4	70	30
5	70	30
6	70	30
7	70	30
8	71	29
9	71	29
10	71	29
11	72	28
12	72	28
13	72	28
14	72	28
15	72	28
16	72	28
17	72	28
18	72	28
19	71	29
20	70	30
21	70	30
22	69	31
23	69	31
24	67	33
25	67	33
26	66	34
27	67	33
28	67	33
29	67	33
30	67	33
31	67	33

	Rain chance (%)	Snow chance (%)
1	27	7
2	26	7
3	26	7
4	26	8
5	26	8
6	26	8
7	25	9
8	25	9
9	24	9
10	24	10
11	23	10
12	23	10
13	22	10
14	21	11
15	21	11
16	21	11
17	21	12
18	21	12
19	21	13
20	21	13
21	21	14
22	22	14
23	22	15
24	23	16
25	23	16
26	24	17
27	24	17
28	24	17
29	24	17
30	24	18
31	24	18

	Dry (%)
1	100
2	100
3	100
4	100
5	100
6	100
7	100
8	100
9	100
10	100
11	100
12	100
13	100
14	100
15	100
16	100
17	100
18	100
19	100
20	100
21	100
22	100
23	100
24	100
25	100
26	100
27	100
28	100
29	100
30	100
31	100